#pragma once

// NOTE : The following MIT license applies to this file ONLY and not to the SDK as a whole. Please review the SDK documentation 
// for the description of the full license terms, which are also provided in the file "NDI License Agreement.pdf" within the SDK or 
// online at http://new.tk/ndisdk_license/. Your use of any part of this SDK is acknowledgment that you agree to the SDK license 
// terms. The full NDI SDK may be downloaded at http://ndi.tv/
//
//*************************************************************************************************************************************
// 
// Copyright(c) 2014-2020, NewTek, inc.
// 
// Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation 
// files(the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, 
// merge, publish, distribute, sublicense, and / or sell copies of the Software, and to permit persons to whom the Software is 
// furnished to do so, subject to the following conditions :
//
// The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
// 
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF 
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// WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
//
//*************************************************************************************************************************************

// It is important when using video to realize that often you are using difference clocks
// for different parts of the signal chain. Within NDI, the sender can send at the clock rate
// that it wants and the receiver will receive it at that rate. The receiver however is very
// unlikely to share the exact same clock rate in many cases. For instance, bear in mind that
// computer clocks rely on crystals which while all rated for the same frequency are still not
// exact. If you sending computer has an audio clock that it "thinks" is 48000Hz, to the receiver
// computer that has a different audio clock this might be 48001Hz or 47998Hz. While these 
// differences might appear small they accumulate over time and can cause audio to either 
// slightly drift out of sync (it is receiving more audio sample than it needs to play back)
// or might cause audio glitches because it is not receiving enough audio samples. While we
// have described the situation for audio, the same exact problem occurs for video sources;
// it is commonly thought that this can be solved by simply having a "frame buffer" and that
// displaying the "most recently received video frame" will solve these timing discrepancies.
// Unfortunately this is not the case and when it is done because of the variance in clock 
// timings, it is very common the video will appear the "jitter" when the sending and 
// receiving clocks are almost in alignment. The solution to these problems is to implement
// a "time base corrector" for the video clock which is a device that uses hysteresis to know
// when the best time is to either drop or insert a video frame such that the video is most
// likely to play back smoothly, and audio should be dynamically audio sampled (with a high
// order resampling filter) to adaptively track any clocking differences. Implementing these
// components is very difficult to get entirely correct under all scenarios and this 
// implementation is provided to facilitate this and help people who are building real time
// video applications to receive audio and video without needing to undertake the full 
// complexity of implementing such clock devices. 
//
// Another way to look at what this class does is that it transforms "push" sources (i.e.
// NDI sources in which the data is pushed from the sender to the receiver) into "pull" 
// sources in which a host application is pulling the data down-stream. The frame-sync
// automatically tracks all clocks to achieve the best video performance doing this 
// operation. 
//
// In addition to time-base correction operations, these implementations also will automatically
// detect and correct timing jitter that might occur. This will internally correct for timing
// anomalies that might be caused by network, sender or receiver side timing errors caused
// by CPU limitations, network bandwidth fluctuations, etc...
//
// A very common use of a frame-synchronizer might be if you are displaying video on screen 
// timed to the GPU v-sync, you should use such a device to convert from the incoming time-base
// into the time-base of the GPU.
//
// The following are common times that you want to use a frame-synchronizer
//     Video playback on screen : Yes, you want the clock to be synced with vertical refresh.
//     Audio playback through sound card : Yes you want the clock to be synced with your sound card clock.
//     Video mixing : Yes you want the input video clocks to all be synced to your output video clock.
//     Audio mixing : Yes, you want all input audio clocks to be brought into sync with your output audio clock.
//     Recording a single channel : No, you want to record the signal in it's raw form without any re-clocking.
//     Recording multiple channels : Maybe. If you want to sync some input channels to match a master clock so that
//                                   they can be ISO edited, then you might want a frame-sync.

// The type instance for a frame-synchronizer
typedef void* NDIlib_framesync_instance_t;

// Create a frame synchronizer instance that can be used to get frames
// from a receiver. Once this receiver has been bound to a frame-sync
// then you should use it in order to receive video frames. You can 
// continue to use the underlying receiver for other operations (tally,
// PTZ, etc...). Note that it remains your responsibility to destroy the
// receiver even when a frame-sync is using it. You should always destroy
// the receiver after the frame-sync has been destroyed.
PROCESSINGNDILIB_API
NDIlib_framesync_instance_t NDIlib_framesync_create(NDIlib_recv_instance_t p_receiver);

// Destroy a frame-sync implementation
PROCESSINGNDILIB_API
void NDIlib_framesync_destroy(NDIlib_framesync_instance_t p_instance);

// This function will pull audio samples from the frame-sync queue. This function
// will always return data immediately, inserting silence if no current audio
// data is present. You should call this at the rate that you want audio and it
// will automatically adapt the incoming audio signal to match the rate at which
// you are calling by using dynamic audio sampling. Note that you have no obligation
// that your requested sample rate, no channels and no samples match the incoming signal
// and all combinations of conversions are supported. 
// 
// If you wish to know what the current incoming audio format is, then you can make a call
// with the parameters set to zero and it will then return the associated settings. For instance
// a call as follows :
//     NDIlib_framesync_capture_audio(p_instance, p_audio_data, 0, 0, 0);
//
// will return in p_audio_data the current received audio format if there is one or sample-rate
// and no_channels equal to zero if there is not one. At any time you can specify sample_rate and
// no_channels as zero and it will return the current received audio format.
PROCESSINGNDILIB_API
void NDIlib_framesync_capture_audio(// The frame sync instance data
                                    NDIlib_framesync_instance_t p_instance,
                                    // The destination audio buffer that you wish to have filled in.
                                    NDIlib_audio_frame_v2_t* p_audio_data,
                                    // Your desired sample rate, number of channels and the number of desired samples.
                                    int sample_rate, int no_channels, int no_samples);
PROCESSINGNDILIB_API
void NDIlib_framesync_capture_audio_v2(// The frame sync instance data
                                       NDIlib_framesync_instance_t p_instance,
                                       // The destination audio buffer that you wish to have filled in.
                                       NDIlib_audio_frame_v3_t* p_audio_data,
                                       // Your desired sample rate, number of channels and the number of desired samples.
                                       int sample_rate, int no_channels, int no_samples);

// Free audio returned by NDIlib_framesync_capture_audio
PROCESSINGNDILIB_API
void NDIlib_framesync_free_audio(// The frame sync instance data
                                 NDIlib_framesync_instance_t p_instance,
                                 // The destination audio buffer that you wish to have filled in.
                                 NDIlib_audio_frame_v2_t* p_audio_data);
PROCESSINGNDILIB_API
void NDIlib_framesync_free_audio_v2(// The frame sync instance data
                                    NDIlib_framesync_instance_t p_instance,
                                    // The destination audio buffer that you wish to have filled in.
                                    NDIlib_audio_frame_v3_t* p_audio_data);

// This function will tell you the approximate current depth of the audio queue to give you an indication
// of the number of audio samples you can request. Note that if you should treat the results of this function
// with some care because in reality the frame-sync API is meant to dynamically resample audio to match the
// rate that you are calling it. If you have an innacurate clock then this functon can be useful.
// for instance :
//
//  while(true)
//  {   int no_samples = NDIlib_framesync_audio_queue_depth(p_instance);
//      NDIlib_framesync_capture_audio( ... );
//      play_audio( ... )
//      NDIlib_framesync_free_audio( ... )
//      inaccurate_sleep( 33ms );
//  }
//
// Obviously because audio is being received in real-time there is no guarantee after the call that the
// number is correct since new samples might have been captured in that time. On syncronous use of this
// function however this will be the minimum number of samples in the queue at any later time until
// NDIlib_framesync_capture_audio is called.
PROCESSINGNDILIB_API
int NDIlib_framesync_audio_queue_depth(NDIlib_framesync_instance_t p_instance);

// This function will pull video samples from the frame-sync queue. This function
// will always immediately return a video sample by using time-base correction. You can 
// specify the desired field type which is then used to return the best possible frame.
// Note that field based frame-synchronization means that the frame-synchronizer attempts
// to match the fielded input phase with the frame requests so that you have the most
// correct possible field ordering on output. Note that the same frame can be returned
// multiple times.
//
// If no video frame has ever been received, this will return NDIlib_video_frame_v2_t as 
// an empty (all zero) structure. The reason for this is that it allows you to determine
// that there has not yet been any video and act accordingly. For instance you might want
// to display a constant frame output at a particular video format, or black.
PROCESSINGNDILIB_API
void NDIlib_framesync_capture_video( // The frame sync instance data
                                     NDIlib_framesync_instance_t p_instance,
                                     // The destination audio buffer that you wish to have filled in.
                                     NDIlib_video_frame_v2_t* p_video_data,
                                     // The frame type that you would prefer, all effort is made to match these.
                                     NDIlib_frame_format_type_e field_type NDILIB_CPP_DEFAULT_VALUE(NDIlib_frame_format_type_progressive));

// Free audio returned by NDIlib_framesync_capture_video
PROCESSINGNDILIB_API
void NDIlib_framesync_free_video( // The frame sync instance data
                                  NDIlib_framesync_instance_t p_instance,
                                  // The destination audio buffer that you wish to have filled in.
                                  NDIlib_video_frame_v2_t* p_video_data);